Despite advancements in localization technologies, mobile users are still finding problems with their map and nagivation services. For example, in a downtown area where high rises create an “urban canyon,” location derived from a global positioning system (GPS) can be off by more than a block. The many different buildings in urban areas have different properties due to varied building materials.
For example, the process by which satellites calculate GPS data is adversely affected by the different reflectants in building materials. These varied materials, along with increased building density in cities, has created urban canyons where GPS users receive inaccurate information about their location.